Two methods of measuring ionization energy, photo-ionization, and electron bombardment, are shown. A high vacuum system is used with a simple cell to measure electric conductivity of gases. The photo-ionization of sodium by the use of a mercury light source and a monochromator is carried out. The electron-bombardment method is then demonstrated with sodium and three noble gases. Animation shows what occurs on the atomic level during the ionization process. Ionization energy is defined as the minimum energy needed to remove an electron from a gaseous atom, with energy per mole being a more practical unit to use. Relation of ionization energy to chemical reactivity is explained.
Science Consultant: Professor Bruce H. Mahan, University of California, Berkeley.
Wardâs Volume 15, CHEM Study #4151, 22 minutes. In color, 1989.